Plasma levels of atrial natriuretic peptide (ANP), arginine vasopressin (AVP), renin activity (PRA), aldosterone (PA), catecholamines and urinary prostaglandins (PG), as well as renal function were measured in children in the edematous state of the nephrotic syndrome before and after infusion of human serum albumin. Before albumin infusion, plasma levels of AVP, PRA, PA and noradrenaline (NA) and urinary excretion of PGE2, PGE-Met, PGF(2α) were elevated. The mean value of plasma ANP was in the normal range. Albumin infusion produced a 36% increase in the calculated plasma volume. It was associated with a fivefold rise in the plasma level of ANP (31.6 ± 22.6 vs. 151.4 ± 52 fmol/ml mean, SD), and an significant fall in the levels of PRA, AVP, PA, and NA. Similarly, urinary concentration of PGE2, PGE-Met and PGF(2α) fell. Urine flow, GFR, U(Na)V, FE(Na), and C(Osm) increased significantly, while C(H2O) remained unchanged. The diuresis, natriuresis and GFR correlated with the level of plasma ANP, while urinary sodium excretion did not correlated with PA or NA levels. These findings suggest that ANP plays an important role in albumin induced natriuresis in children with nephrotic syndrome.
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